Gureyev Timur E, Kozlov Alexander, Nesterets Yakov I, Paganin David M, Martin Andrew V, Quiney Harry M
ARC Centre of Excellence in Advanced Molecular Imaging, School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia.
Faculty of Health Sciences, University of Sydney, Sydney NSW 2006, Australia.
IUCrJ. 2018 Sep 15;5(Pt 6):716-726. doi: 10.1107/S2052252518010941. eCollection 2018 Nov 1.
It is shown that the average signal-to-noise ratio (SNR) in the three-dimensional electron-density distribution of a sample reconstructed by coherent diffractive imaging cannot exceed twice the square root of the ratio of the mean total number of scattered photons detected during the scan and the number of spatially resolved voxels in the reconstructed volume. This result leads to an upper bound on Shannon's information capacity of this imaging method by specifying the maximum number of distinguishable density distributions within the reconstructed volume when the radiation dose delivered to the sample and the spatial resolution are both fixed. If the spatially averaged SNR in the reconstructed electron density is fixed instead, the radiation dose is shown to be proportional to the third or fourth power of the spatial resolution, depending on the sampling of the three-dimensional diffraction space and the scattering power of the sample.
结果表明，通过相干衍射成像重建的样品三维电子密度分布中的平均信噪比（SNR）不能超过扫描期间检测到的散射光子平均总数与重建体积中空间分辨体素数量之比的平方根的两倍。当传递给样品的辐射剂量和空间分辨率都固定时，该结果通过指定重建体积内可区分密度分布的最大数量，给出了这种成像方法香农信息容量的上限。相反，如果重建电子密度中的空间平均SNR是固定的，根据三维衍射空间的采样和样品的散射能力，辐射剂量与空间分辨率的三次方或四次方成正比。
